Bacterial conjugation is the bacterial counterpart of sexual reproduction. Also known as horizontal gene transfer, it involves the transfer of genetic material from one F+ or Hfr bacterium to another F+ or F- bacterium.
The F or fertility factor is a crucial component of the bacterial plasmid and it accounts for the development of sex pili which are important for conjugation. An F+ cells contains the F-factor incorporated into its plasmid, whereas an F- cell lacks the F-factor and therefore cannot participate in conjugation.
Conjugation between an F+ and F- cell can result in the transfer of the F-factor to the F- bacterium.
An Hfr bacterium contains F-factor incorporated into its circular genome.